Ultrasound-Assisted Enzymatic Coagulation in Fresh Goat Cheese Production: Optimization of Recombinant Chymosin Activity, Curd Drainage Kinetics, and Enhancement of Technological Properties

Abstract Goat milk cheese production is gaining attention due to its nutritional value and potential for niche markets. However, technological challenges, mainly curd fragility and low yield, often limit large-scale processing and quality standardization. Thus, this study investigated the use of ultrasound (US) during milk coagulation as a strategy to enhance curd formation and cheese-making efficiency. The impact of US on recombinant chymosin activity was first assessed, showing that short sonication (5 min at 30 °C) increased proteolytic activity by up to 92% and milk-clotting activity by 22% ( p < 0.05). During coagulation, US reduced rennet coagulation time by up to 10%. Partial US-assisted coagulation (8 and 16 min) increased spontaneous syneresis (from 2 to 7% after 40 min), reduced curd mass loss during drainage (≤ 34%), and enhanced solid retention in the gel (up to 45% reduction in whey solids). These effects resulted in cheeses with higher yield (up to 39.5%) and increased protein (≤ 5%) and fat content (≤ 11%). Compared with the control cheese, those produced with US intervention exhibited higher proteolysis, greater elastic modulus, and improved elasticity after 21 days at 7 °C, without significant changes in pH, acidity, or color. Therefore, partial US-assisted coagulation (8 and 16 min) enhanced recombinant chymosin activity and induced colloidal changes in the milk matrix, contributing to improved coagulation efficiency and technological properties of fresh goat cheese, including higher yield, greater solids retention, and better texture. These findings highlight ultrasound as a promising tool to optimize goat cheese production and improve process efficiency in the dairy industry.